[PATCH v7] eal: add seqlock

[Morten Brørup]

(Resent with Konstantin's new email address.)

> From: Mattias Rönnblom [mailto:mattias.ronnblom at ericsson.com]
> Sent: Sunday, 15 May 2022 14.40
> 
> Two questions remain:
> 
> 1) Should the seqlock and the seqcount reside in different header
> files?
> 2) Is it it good enough to provided only a spinlock-protected seqlock?
> 
> Question 1 I don't really have an opinion on. Both ways seems perfectly
> reasonable to me. I noted Morten wanted a split, and left to my own
> devices this is probably what I would do as well.

Argument for separate header files: If we add e.g. a rte_seqticketlock_t later, it should be able to include the rte_seqcount_t header file without also getting the contextually irrelevant rte_seqlock_t type and functions.

I don't feel strongly about this.

> 
> I think the answer to 2 is yes. We can provide other variants in the
> future, would the need arise.

Agree.

> 
> <snip>

Please move the header files from /lib/eal/include to /lib/eal/include/generic, where the other lock header files reside.